Method of detinning tin-scrap.



110.883,411. PATENTBD MAR. 31, 190s.

M. LEITGH. l

METHOMF 1151111111111; TIN SCRAP. APPLIUATION FILED MAY 17. 1907. RENEWED JAN. 10, 1908.

z SHEETS-SHEET 1.

M. LEITCH.

MBTHDD 0F DE'TIN'NING TIN SCRAP.

APPLICATION FILED MAY 17, 1907. RENEWBD 11111.10, 190s.

2 SHEETSr-SHBET 2.

PATENTED MAR. 31, 1908.

UNITED LsTATEs Pif-WENT oEEroE.

MEREDITH LEITCH, OF ELIZABETH, NEW JERSEY, ASSIGNOR TO METAL PROCESS COMPANY,

' A CORPORATION Ol" NEW YORK. i

METHOD OF DETINNING TIN-SCRAP.

Specification of Letters Patent.

Patented March s1, l190s.

i Original application filed November 30,- 1906, Serial No..345,815.' Divided Vand this application filed May 17 '1907,

Serial No. 374,131. Renewed January 10, 1908. Serial No. 410,199.

To all whom it may concern:

Be it known that I, MEREDITH LEITCH, a

citizen of the United States, residing' at Elizabeth, county of Union, New Jersey,

have invented certain new and useful `Im-v tinning, as now practiced.

The presence of air and other gases in the `detinning chamber and in theA tin scrap prevents or hinders the action of the drychlorin by diluting it and by keeping it out of the folds and minute spaces in the tin scrap.

In carrying out my invention the tinscrap is submerged in liquid stannic chlorid introduced at the bottom of the chamber and entirely filling the chamber. This drives out all the gases from the chamber and the spaces in the tin scrap so that when the liquid iswithdrawn t 1e dry chlorin will follow in after and c ome in Contact with all the surfaces of the tin scrap in as pure and undiluted a state as it can be obtained.

y The action of the undiluted chlorin of the tin is very rapid and. heat is generated. If

' undiluted chlorin is allowed to come suddenly 'in contact withja large body of the tin scrap, the temperature willrise to such a point as to vaporizefthe stannic chlorid (SnClA), causing the vapor to mix with the chlorin and interfere with the process of 'detinning and the 'recovery of the stannicy Inl my process the slow withdrawal chlorid. of the stannic chlorid from the detinning chamber through an opening in the bottomv gradually exposes the scrap above the liquid to chlorin and permits ofso controlling the recess that too great a rise in temperature 1s prevented. 'lhe'res'ult is that the scrap is more uniformly detinned' and the stannic chlorid formed is prevented from vaporizing and interfering with the process. 4

When stannic chlorid is caused to` iiow -through the tin scrap from above in combination with chlorin, the chlorin is-greatlyl dissolved by the stannic chlorid and must-be eliminated bya separating process, requiring quietly from the bottom, in order to drive out the gases and is withdrawn in the same Way. The absorption ofthe chlorin isthereby practically avoided, as the stannic chlorid presents only a level and 'undisturbed surace.

In detinning ordinary tin scrap some organic matter, and anhydrous carbons Will be present unless carefully removed, and these will form with the chlorin hydrochloric acid (HC1) which is an undesirable element in the stannic chlorid.` This hydrochloric acid whenl anhydrous is al gas at ordinary pressures and temperatures and is absorbed y the stannlc chlorid generated 1n the chamber. In my process I usey a purifying 'chamber through which all the liquid prod- SJSS.

nely

uct of, the detinning chamber must This chamber contains tm A1n very divided form which reacts upon the hydrochloric acid converting it into stannic chlorid and' hydrogen. The latter is allowed to escape and not interfere with the chlorin in the detinning chamber. In this purifying chamber any 4dry chlorin dissolved in the stannic chlorid is also acted upon and converted into stannic i chlorid, so that the so w liquid product of the process will not contain free chlorin.

f' In detinning with dry chlorin, the stannic chlorid forms in globules on the tin scrap and` obstructs the action of the chlorin on the tin whenever the temperature of the chamber is below the boiling point of thc stannic chlorid, Moreover, the gases `generated in the process and not absorbed and any gases admitted along with the chlorin and not absorbed, interfere with the action of the chlorin by diluting it and later filling the chamber and stopping the inflow of chlorin and the detinning process. l On the contrary in my process, the chlorin supplyis cut olf whenever such conditions arise and the detinning chamber is filled from thebottom withV liquid stannic chlorid, which collects; the'globules of stannic chlorid adhering lto the scrap and drives `out theinert and interprocess provides for collectin the stannic' chlorid by a final submersion o the detinned steel in stannic chlorid, thus causing the globules to join in the general mass of liquid, and on withdrawing the liquidthere is created a high degree of vacuum to vaporize thestannic chlorid which remains as moisture and in the minute spaces. This vaporized stannic chlorid is thus condensed on the cool walls of the detinning chamber, resulting in a saving of the stannic chlorid and removal of it from the steel and making it1v less disagreeable and harmful to the workmen.

In handling stannic chlorid it has heretofore been difficult to prevent its coming in contact with the air and moisture. In my process I provide for handling the stannic chloridby pressure' from above, the stannic chlorid exerted by another liquid having no affinity, such as sulfuricacid (H2504). 'j This latter being also affected by contactl with the air and difficult to pump is covered by a third liquid which may be' readily pumped andcome in contact with the air, but which has no affinity for the second liquid. Fo'r this third li uid I use petroleum. The different speci 1c gravities are such as to cause them to remain one above the other in the order named and desired. j f

In detinning with stannic chlorin it is dinicult to obtain tight joints between parts of the apparatus separated from each other, as, for instance, the cover of the detinnin chamber. -It is also difficult to regulate t ie ltemperature of the detinning chamber. In the apl-paratus for carrying out my process, these d iculties are obviated by providing a seal *which resists the ressure when in use, being at that time in t e form of a solid cement and is li uid when the arts are to be separated. %Vith this seal) I combine a coil through which ysteam 'or a cooling fluid can be passed, as desired,for melting or solidifying the seal, as re uired, and-for controlling the temperature oflthe detinnin chamber.

In order to avoid any distur ances when a vvacuum is created above the stannicchlorid by mechanical means or by gravity causing the li Luid to vaporize I use a cooling chamber whfdh 7 is located sufficiently below the detinning chamber so that the liquid contained therein will not be drawn up when the vacuum is formed in the detinning chamber, havin means to quickly reduce .the temperature o the' liquid and prevent its vaporizing soas' to interfere with the forming of the vacuum or otherwise interfering with the carrying out of the process.

The following is a description of my process and apparatus for carrying it out, reference being had to the accompanying drawings, in which Figure 1 represents the a paratus, Fig. 2 represents a. modification o the means for controlling the stannic chlorid.

Referring more particularly to the drawings, A represents the-"detinning chamber having within it the perforated removable basket B- containing tin scrap. This chamber has a double wallforminga s` ace surrounding the chamber, within w ich is a quantity of paraffin C, and also a coil D the upper end of which E is connected with a steam inlet controlled by the cock e, and a water outlet controlled by the cock e The vlower end of this coil is connected with an outlet for condensed steam controlled by the l cock e0 and with an inlet for cold watercoutrolled by the cock e4. When steam is admitted to the coil D the paraffin is melted so that the cover A with its depending flange can be easily removed. When the cover is in place and cold water is passed through the coil D, the araffin. is hardened so as to seal the cover with a solid cement, making an air and gas tight joint. The passage of the cold water through the coil D also reduces the temperature of the space within the chamber A. A pipe F enters the chamber from below and has at its upper end a terminal F entering the cap A2 of the cover A. This termivnal'is connected with the portion F by a swivel joint F2 so that itcan be turned to one side in order to permit the removalland insertion of the basket B. A gage having a glass portion G has one end connected to the pipe F, and the other end connected to the bottom of the chamber A so as to indicate theheight of the liquid within the chamber. The pipe F is branched, one branch leading to an air inlet H having aninwardl opening check valve H and a cock H2 an the other branch leading toan inlet I for admitting dry chlorin having an inwardly opening check valve Il and a sto cock I2.

From t e bottomof the detinning chamber leads a pipe J, which has a valve K and is connected to -a vent 1pipe L having an outwardly opening chec valve L and a stop cock L2. A second detinning chamber A20 similar to the detinning chamber A'is connected to the inlets H and I and the vent L by corresponding passages F20 and I20. A third detinning chamber A30 is also connected to the inlets H and I and the vent L by ipes F30 and J00 corresponding to the pipes and J, andhaving corresponding stop cocks.

The pipes J, J20 and J00 are connected by branches M', M2 and M0 to a purifying chamber N, which is surrounded by a water jacket O, through which cold water continually passes. The cover of'this purifying cham-- er is connected with a vent pipe P having an outwardly opening check 'valve P -The pipes M M2, M3 are provided with sto cocks m, m2, m0. The purifyingchaniber is iilled with pure .tin N in some iiiiely divided form. A pifpe Q passes through the bottom of the puri ying chamber iT of, and is provided with a stop cock Q. This pipe leads to a holder R which contains a suficient amount of anhydrous stannic chlorid to slightly more than lill the detinning chamber A. This holder is provided with .a drawi off cock R for drawing oil the stannic chlorid as desired. TheY pipe Q. is provided with a second stop cock Q2, around which is a bypass containing a pump S. This b'y-pass has stop cocks S S2 so that the pump can be cut as dry air.

out when the stop cock Q2 is open, and the stop cock closed when the assage through the pump is open. The holdp ble wall containing a liquid seal R2, into which dips the iiange of the counterweighted cover R0. The space within the cover above stannic chlorid is filled wit'h an inert gas such A gage having a glass portion T is connected with the holder 1R., the ower end of the gage being connected to the bottom of' the holder R, and the upper end being connected with the pipe which extends above the stannic chlorid within the holder.

chlorid to iill the detiiining c In Fig. 2 a modified forni of the holder 'and means for handling the stannic chlorid is provided. In this form the pipe q corresponding to the pipe Q in Fig. l is connected directly to the bottom of aholder Y provided withiii a draw-oli' cock Y. This holder is of such size as to contain sul licient staiinic chlorid` to ill the chamber A, the staiinic chlorid when the chamber A is empty rising to the point V2,.and also a slightly greater amount of' some liquid ol' smaller specific gravity than'staiinic chlorid, and which will not combine therewith, such, for instance, as sulfuric acid, and also a layer ol' a still lighter iluid which will not combine with the sulfuric acid, such as petroleum. A gage having a glass'portioii V has its lower end connected wit-h the lower sions'ol petroleum, sulfuric acid aiidstannic chlorid which correspond in height to the divisions in the holder Y. end of the holder Y leads a pipe W, which is connected to the bottoni of a second "holder X lia-ving an air vent X. by-passes, one of which contains a stop cock W while the other contains stop cocks W2, W3 and a pump W2. Y In cari' ing out m recess by the apparatus of 41ig'. 1, the lio der R must contain a suficient amount of anh drous staiinic liamber A, and

nearlyto the top thereer R has a dou-v From the upper the valves-that would expose-the tin chloridtin scrap should be dry. The cover is now replaced and the paraffin seal hardened by .admitting cold water through theI coil D ini stead of steam. The detiniiing chamber A20 is filled with tin scrap and sealed from the atmosphere. A communication through the system of pi )es from chamber A to chamber A20 is made by opening valves H2 H20 in the piping connections from the top of chamber A- toward the top of chamber A20 ,and the valves K20 and L20 from the bottom of chamber A20 tothe vent L. The stannic chlorid is now forced up into the detinning chamber A until it has reached the top and driven out by displacement air and othergases tlirou h` the lpipes F F -and chamber A20 and vent `The valve H2 is now closed and valves I2 and Q2 opened and the stannic chlorid allowed to quietly descend to the holder. Clilorin gas will now flow through the check valve I and the valve 1'2into chamber A at constant pressure and fill the space above the descending staiinic chlorid and act on the tin scrap. When all of the chlorid hasdescended and been withdrawn from the chamber, the chlorin will continue to iow in at constant pressure and detin the tin scrap, converting it into stannic chlorid until the inert gases unavoidably contained in the chlorin' fill the chamber and' prevent further entry of chlorin. During this process of absorbing the chlorin, cold water is kept in circulation through the coil D so asto absorb the heat .of chemical action and control the temperature of the chamber, keeping it below boilingpoint of stannic chlorid. At the same time the chlorid is condensed on the tin scrap and on thev cool walls of the chamber and runs down through the purifying chamber N into the holder. The presence of the purifying chamber results in always maintaining the tin chlorid within the holder free from chloric acid (HC1) formed in the chamber into stannic chlorid. When the chlorin has ceased to How into the chamber A, or the iiow is very slow, the valve l2 in the .chlorin inlet is closedand valve .l-l2 opciied,ithus tablishing again communication from chiinrber A with chainber'A20 and from chai'nbei A20 through valve L20 to the vent. Stannie. chloriii is nowagainpumped up.` into thc throu h chamber' A20 Ato the vent.' The tin scrap ein now submerged in stannic chicrid, the -g obules` of stannic chlorid which would otherwise adhere to the tin scrap will dissolved cliloriii and converts the hydrochamberv A and the inert gases driven out.l A

be absorbed in the stannic chlorid and will be carried down into the holder R when the stannic chlorid is withdrawn. The valve ll2 is new again closed and I2 opened and the stannic chlorid again allowed to return to the holder and the chlorin to again flow int-o the chamber to complete the operation of detinning. This operation is to be repeated as often as found necessary by observation to completely remove the tin from the tin scrap. When the detinning is completed the valve l2 is closed and the valve ll'l opened andthe gaseous contents of chamber A driver out to thc` vent through chamber A20 bu the stannic chlorid as previously described, the chlorin mixed with the gases driven out being absorbed by the tin on the tin scrap in chamber A20. The valve H2 is now closed and the stannie chlorid in chamber A allowed to return to the holder, which being situated a sufficient distance below the chamber A will act to create within lthat chamber a high degree of vacuum and the stannic chlorid remaining on the detinned scrap at the time of withdrawing the stannicA chlorid (the chamber and contents having been kept at proper temperature) will be vaporized by the heat in itself and the heat in the detinned scrap mass and condensed on the walls of the chamber cooled by thc circulation of water through the cooling copl. At the saine time the stannic chlorid in the purifier must ,be sutliciently cooled to prevent evaporation which would otherwise occur on account of the'lowered pressure. lVhen the condensed stannic chlorid has drained out of chamberA the valve K immediatelybelow it is closed and valve Il'Z opened and air admitted through pipe H from the blower H3 to break the vacuum in the chamber and expel the gases. The air is preferably heated. The cooling water is new shut oil from the ycoil D and steam turned in to it to melt the parafiin in the seal, the cover is removed and the basket with the detinned scrap taken out and another basket "containing new tin scrap placed in the chamber. that the stannic chlorid in chamber A is being condensed, the cover removed and the detinned scrap removed, new tin scrap is put into chamber A and the cover replaced and sealed.. The operation ot detinning is now carried on in chamber A2 venting into chamber Aw thc same as described l'or thc operation of chamber A to chamber ,-V, when connected wit-h chamber Chamber A20 is also used in connection with clfamber A in the same wav. From time to time the accumulation of tin chlorid in the holder is drawn oll'.

'l`he arrangcimnt oll Fig. 'l is l'or the purpose ol' avoiding passing the stannic chlorid through a pump which is attended with some dilliculties. ln this apparatus the holder has a plpe connectlon i'rom its lowest point During the time.

to the purilier and a pipe connection from its highest point te the pump with a by-pass around. the pump to the lowest point of another vessel open to the atmosphere at its highest point. A Petroleum and another liquid as HZSO4 whichv is not affected by stannic chlorid, fills the space in the holder above the stannic chlorid; also there is sull'icient petroleum in-the other vessel to equal the contents of one of the detinning chambers. The stannic chlorid 'is caused to rise through the pipe A and the purifier filling the detinning chamber by )umping petroleum into the holder above tlie llZSQ, and SnCl4 and forcing the former downward and the SDCL, out at the bottom and up into the dc.- tinning chambers.

The chambers and pipes etc. are preterably made ot iron since it is butlittle attacked by the gases and liquids present.

The apparatus described but not claimed herein is claimed in my copending applica tion Serial No. 345,815 filed Nov. 30, 1906 of which this is a division.

What l claim'is:

1. The process of detinning tin serai which consists in surrounding the scrap ai ternately with dry chlorin gas and with anhydrous stannic chlorid.

2. rl`he process of detinning tin scrap which consists in surroundin the scrap with t anhydrous stannic chlorid w iile in a closed chamber and thereby expelling the gases from saidchamber and then witlulrawing said .1 stannie chlorid and surrounding said scrap 100 with anhydrous chlorin gas.

3. The process of detinning tin` scrap, which consists in surrounding the tin scrap with anhydrous chlorin gas in a closed chamber and expelling said gas by surrounding 105 said scrap with anhydrous stannic chlorid.

4. The processof detinning tin scrap, which consists in surrounding the tin scrap with anhydrous chlorin gas in a closed chamber and expelling said gas by surroundinr 110 said scrap with anhydrous stannic chlori( and then creating a vacuum within the chamber containing said sera F The process of detinning tin scrap,

o. which consists in surrounding the tin scrap with anhydrous chlorin gas in a closed chamber and expelling said gas by surrounding said scrap with anhydrous stannie chlorid, then creating a vacuum within the chambcr containing said scrap and then cooling said chamber so as to condense any vapors therein.

6. rl`he process ot detinning tin scrap, which consists in surrounding the tin scrap 4 with anhydrous chlorin gas in a closed cham 125 ber and expelling said gas by surrounding said scrap with anhydrous chlorin, then cre ating -a vacuum within the chamber containing said scrap, then cooling said chamber so as to confiense any vapors therein, and then admitting air to expelany remaining gases orvaors.'`

7. ghe process of detinning tin scrap, which consists in surrounding the tin scrap with anhydrous `chlorin gas in a closed cham.- ber'and expelling said gasby surrounding said scrap with .anhydrous chlorin, then creating a vacuum withinthe'chai'nber containing said scrap, then cooling said chamber yso as to condense any vapors therein, then .admitting air to expel any remaininggases or vapors, and causing said gas and vapors topass through another charge of -ti-n scrap in another closed chamber.

8. The process of detinning tin Y scrap,

which consists in causingstannic chlorid to flow into andout of a closed chamber con taining tin scrap at the bottom of said cham- A on the stannic chlorid so as to dis lace an amount of said chlorid that is smaler thanl the amount of said inert fluid. y i

10. In a process of detinning tin scrap the improvement which consists in causing stanynic chlorid to submerge tin scrap by causing an inert fluid of lesser specific gravity than` stannic chlorid to exert a varying. pressure on the stannic chlorid so as to dis lace an amount of said chlorid that is sma er than the amount of said inert ,fluidi through the varying pressure on a thirdl fluid inert rela- 12. The process of .whichconsists in forcing all the gases `out"of tively to the said second fluid and of smaller specific gravity than said second fluid, thel varying pressure of said iuid being brought about by mechanical means.

11. l In a process of detinning tin scrap by chlorin, the improvementswhich consist in gradually exposing the tin scrap to chlorin` by submerving in arelatively inert liquid and gradua ly withdrawing saidliquid in the presence'of chlorin. detinning tin scrap the tin lscrap bycausing an inert liquid to rise so as to cover it and then drawin .chlorin intol the lscrap by withdrawing sai liquid in the presence of chlorin.

13. The rocess of detinning tin lscrap which consists -in converting the tinl from tin scra in a closed' chamber into stannic chlorid lmeans of an anhydrous chlorin gas, expe ling thegases from said chamber, creating a vacuum therein, condensing the vapors therein and maintaining 'thjeconf densed vapors in liquid form by reason-of the reduced temperature.y l

14. The' process of 'detinnin tin scrap which consists infconverting t e tin from tin sc ra lin `afclosed chamber into stannc chlorid gas,'expelling the gases from said-chamber,

lcreating a lvacuum therein; condensing the vapors therein maintaining the condensedva- ,y pors in liquid form by reason of thereducedtemperature, and expelling the. uncondensed VaPQIS and ases by air prior to the opening ofthe cham er. l v

Witnesses: W. P. PALMER,

L. A. WELLES.

y means of an anhydrous chlorin MEREDITH LEiTcHQ 

